1. 3.5 Energy and Nutrition One hour of swimming uses 2100 kJ of energy.
Learning Goal Use the energy values to calculate the kilocalories (kcal) or kilojoules (kJ) for a food.

2. Calorimeters Nutritionists burn food in a calorimeter that
is used to measure heat transfer.
consists of a steel container filled with oxygen and a measured amount of water.
indicates the heat gained by water, which is the heat lost by a sample during combustion.
In a calorimeter, the burning of a food sample increases the temperature of the water, which is used to calculate the energy value of the food.

3. Calorimeters Measure Energy Values
Heat released
from burning a food sample in a
calorimeter is used to determine
the energy value for the food.

4. Energy and Nutrition
On food labels, energy is shown as the nutritional Calorie, written with a capital C. In countries other than the United States, energy is shown in kilojoules (kJ).
1 Cal = calories
1 Cal = 1 kcal

5. Caloric Food Values The caloric or energy value for 1 g of a food
is given in kilojoules (kJ) or kilocalories (kcal).
The typical energy values are different for each food type.

6. Energy Values for Some Foods

7. Guide to Calculating Energy from Food

8. Study Check
A cup of whole milk contains 13 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. How many kilocalories does a cup of whole milk contain? (Round the final answer to the tens place.) A. 50 kcal B. 80 kcal C. 170 kcal

9. Solution
A cup of whole milk contains 13 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. How many kilocalories does a cup of whole milk contain? STEP 1 State given and needed quantities.
ANALYZE Given Need
THE PROBLEM g carbohydrate
9.0 g fat
9.0 g protein kilocalories

10. Solution
A cup of whole milk contains 13 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. How many kilocalories does a cup of whole milk contain? STEP 2 Use the energy value for each food type and calculate kJ or kcal rounded off to the tens place. 13 g carbohydrate × 4 kcal/g = 50 kcal 9.0 g fat × 9 kcal/g = 80 kcal 9.0 g protein × 4 kcal/g = 40 kcal

11. Solution
A cup of whole milk contains 13 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. How many kilocalories does a cup of whole milk contain? STEP 3 Add the energy for each food type to give the total energy from the food. Total energy = 50 kcal + 80 kcal + 40 kcal = 170 kcal

12. Chemistry Link to Health: Weight Loss
The number of kilocalories or kilojoules needed in the daily diet of an adult depends on gender, age, and level of physical activity.
A person loses weight when food intake is less than energy output.